Field of the Invention
The present invention relates to a vacuum installation provided with a cyclone separation unit and more particularly to a cyclone separation unit that can handle different flow rates and allows effective real-time flushing. The invention also relates to the use of such a device.
Description of the Related Art
Vacuum installations, which can be provided on a truck or another kind of vehicle, or as self-supporting independently working units, are used in various capacities for aspirating liquids and particulate materials. They may also be operated in reverse as blowers for delivering particulate material should this be required. The vacuum installations function as air displacement systems and are designed for heavy industrial applications. Such vacuum installations are suitable for suctioning, displacement, transport and/or upload of dry, wet and/or hazardous substances, such as various types of chemical catalysts and/or liquids, gravel, powders, fly ash and sludges. Various configurations exist but in general, all such vacuum installations or vacuum trucks are provided with some form of vacuum chamber to which a vacuum is applied using a vacuum pump of appropriate size for the operation concerned. The vacuum chamber is provided with one or more inlets through which the material to be aspirated may enter the vacuum chamber. This will usually be in the form of a pipe coupling to which a flexible pipe can be attached. As with a household vacuum cleaner, some form of separator must be present between the vacuum chamber and the vacuum pump in order to avoid aspirated material being entrained in the flow through the vacuum pump to the exterior. In existing vacuum trucks, baffles may be provided within the vacuum chamber to encourage large particulates to settle. Filters of various grades may be provided in the vacuum lines leading to the vacuum pump. These may require periodic cleaning to avoid them from becoming blocked.
Another form of separator that has also been used in vacuum trucks is the centrifugal or cyclone type separator. A cyclone separator uses a cyclone chamber with a tangential inlet to create a high speed vortex flow. Particles of solids or liquids will be forced towards the outside of the vortex and relatively clean air is aspirated axially upwards from the centre of the vortex. The cyclone chamber usually has a conical base where the separated materials are funnelled through an outlet leading to a collector below the cyclone chamber. It is noted that filters may still be required downstream from the cyclone to prevent residual particles from entering the vacuum pump. These filters need regular cleaning, which interrupts the operation of the vacuum installation. U.S. Pat. No. 5,996,171 illustrates a vacuum truck system that includes two cyclone separators, each having its own filter that can be alternately flushed. A common final filter cannot be cleaned in this manner. Cyclone separators are very effective in separating large volumes of materials cleanly without relying on a filter as the primary separator. Nevertheless, they can be sensitive to the particular flow conditions. Below a given flow rate the cyclone may not work effectively while at higher flow rates they may become choked, limiting the maximum flow rate at this value.
It would be desirable to provide an improved vacuum installation that alleviated some or all of the above problems.